Process for deasphalting petroleum oils



Jan. 116, 1951 I E. E. WILLAUER 25381320" PROCESS FOR DEASPHALTING PETROLEUM OILS 'Pump U7 i0 g@grid WL-ET WWHDQAWAE El l1 c;

Earl E .QI-'L'Llauer' rzvenjoof Clbboflrleg Jan. i6, 19511 E E. WILLAUER 2,538,220

PROCESS FOR DEASPHALTING PETROLEUM OILS Filed Aug. e, 1947 2 Sheets-sheet 2 DEASPHALTINS TOWER DEASDHALTED OIL OLITLET\,\ A X S4 b S4 c 34 IDIAECIPITANT PHASE 5i --JZ P 50"' 3o IZESIDLILJM ,QESIDLILIM FEED INLET f/ FEED INLET 50 @D ECIDITANT Li 3,1 T IDHASE @EEEID ITANT Y ASPHALT V DHASE ASPHALT PHASE `u4 E pIzEcIPITANT pHA INLET 52 :T -1' l.: I 32 x X 52 'PRECID'ITANT LASPHALT 53, ,NLE-,-

33: 5511K PHASE' hASPI-IALT OUTLET ASPHALT .L

OLITLET .-fZ E-LQ-T'- DEASPHALTED OIL OLITLET QESIDLILIM "-1" "54- G2 FEED INLET) IDIzEc-.IDITHT \DEASI=HALTINS/ ASPHALT Tow/El @i ASPHALT 53: OUTLET OLITLET I F4 I .-5 I

Earl. ElJ'L'LLcIcler Snvembor @SY/(A (27 Clbbolrrze Patented Jan. 16, 1951 PROCESS FOR DEASPHALTING PETROLEUM OILS Earl E. Willauer, Cranford, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application August 6, 1947, Serial No. '766.571

The present invention is concerned with animproved process for removing asphaltic type materials from mineral oils. The invention is more particularly concerned with a process for the precipitation of asphaltic constituents from heavy residua secured in the refining of petroleum oils. The invention is especially directed to a process for the production of high grade deasphalted oils suitable for further processing in cracking equipment and for the production of high grade lubricating oils and the like. In accordance with the present invention, petroleum oils, particularly heavy residua, are contacted with a liquied, normally gaseous, precipitant or with low boiling paramnic type materials in a precipitation zone under conditions such that the asphaltic phase comprises the continuous phase.

It is known in the art to remove asphaltic type materials, normally regarded as saturated polycyclic compounds of high molecular Weights and high carbon to hydrogen ratio from petroleum oils, especially from low gravity residua, by treating these residua with a paraihnic type precipitant such as propane, butane, and the like. The residua treated are usually secured as a result of rening operations comprising normal distillation and vacuum distillation processes. These residua contain asphaltic type materials of high consistency having a softening point above 100 F. and metallic substances Such as iron, sodium, calcium, magnesium, vanadium, nickel, and the like. It is essential that the asphaltic type materials and the metallic elements be substantially removed if these residua are to be further processed satisfactorily. For example, if it is desired to prepare lubricating products of high quality, it is necessary that these constituents be removed, since they tend to form deposits in the engine. Also, if it is desired to further crack these materials in a catalytic cracking process, it is necessary that the undesirable constituents be removed to prevent formation of deposits on the catalyst which greatly decrease the life, activity, and selectivity of the catalyst. It is possible to precipitate the constituents of this type by treating the residua with propane, butane, and the like.

I have now discovered that if a particular method of conducting these deasphalting operations be followed, unexpected desirable improvements are secured. In accordance with my process,I operate the deasphalting zone in such a 'manner that the asphaltic phase comprises the continuous phasel f The process of my invention may be readily 4 Claims. (Cl. 19E-14.46)

understood by the drawings illustrating embodiments of the same. Referring specically to the drawings:

Figure 1 is a diagrammatical sketch of the overall process;

Figure 2 is a diagrammatical sketch showing a conventional deasphalting process and my specic invention and;

Figure 3 illustrates a further embodiment of my process.

- Referring specifically to Figure 1, a residuum feed charge is introduced into the system by means of line l and pump 2. For the purpose of illustration it is assumed that the reed charge comprises a 16% West Texas bottoms based on total crude. This fraction has a gravity in the range of about 10.0 to 10.8 A. P. I. and an initial boiling point in the range of G-850 F.

. The feed stock is passed through heating zone 3 and is introduced* into deasphalting Zone or tower 4. The deasphalting precipitant, which for the purpose of description is taken to be liquied propane, is introduced into the system by means of line 5 and pump 6. This stream is passed through heating zone 'l and is introduced into the bottom of tower l by means of line 8. The percent treat required, that is, the ratio of precipitant to oil treated, is dependent upon the type of residuum processed, but in general, about 250% by volume treat is regarded as the minimum. As high a percent treat may be used as is desired; 30D-400 volume percent treat yields satisfactory results rvwith most residua however.

The system is maintained in a liquid state by operating zone 4 at a pressure of about 100-200 lbs/sq. in. above the vapor pressure, at the operating temperature, of the precipitant used. Usual deasphalting pressures are in the range of 400 to 600 lbs/sq. in. Back pressure regulating valve IB at the top of the tower in withdrawal line I5 is set to provide this pressure.

f- Temperature conditions are adjusted to secure the desired deasphalting of the feed oil. In general elevated temperatures result in increased precipitation. The preferred temperature range when using propane as the precipitant is to 180 F. and with butane ranges up to 305 F. may be used. A temperature gradient along the tower is also desirable to increase the selectivity of precipitation by increasing the internal refluxing action. With propane as the precipitant, a suitable gradient is provided if the bottom of the tower is maintained at about -l55 F. and the top of the tower is maintained at about l40-170 F., the temperature gradient thus being 0 to 60 F.

3 The gradient desired with butano is provided by a temperature of 225-250 F. at the bottom of the tower and 280305 F. at the top of the tower, the gradient thus being 30 to 80 F.

Tower 4 may contain disc and donut type packing or equivalent means adapted to secure contact between the respective phases and the desired distribution of the countercurrently flowing streams. Asphalt phase is withdrawn from tower 4 by means of line 9 and is preferably mixed with an asphalt fluxing oil which. is introduced by means of line l and pump H. A suitable fluxing oil is one boiling in the gas oil range and preferably having a nal boiling point below' the initial boiling point of the residuum. This stream is then passed to a low pressure still or equivalent means, l2, wherein the asphalt is separated from the fluxing oil and from the propane. The asphalt is withdrawn by means of line I3 while the propane and uxing oil are removed by means of line En en -'acordarme''withV my invention, the asphalt-propane `interface is maintained substantially at the point ,ofl intro'- duction ofthe residuum.

The deasphalted oil is removed fromtower i! bymeans of line l', is passedthrough the pressure regulating valve i6, and is then introduced into a high pressure still, El. Temperature and pressure conditions are adjusted in still IT to separate the propane from the oil, the propane beingI removed by means of line I3. It is preferred to partially distill the propane in the high pressure still and to withdrawv the partially propane free oil'by meansv Ofiline it and furtherdistill lthe oil in low pressure still 2E) in order to completely free Vthe oil of precipitant. The remainder of the propane is thus removed by means of line 2|, while the propane freev deasphalted oil is' removed' by means ofi line 22. As pointed' out heretofore, this deasphalted oil is a very desirable stock for further processing in cracking or equivalent processes and also comprises a veryI desirable oil for' the preparation of high Yduality lubricating cil stocks.

Referring now to Figure 2, diagram A illustrates a conventional procedure. for operating the deasphalting tower. In accordance with the conventional procedure, the residuum feed is. introduced into zone 30 by means of line 3l'. The precipitant is introduced' into bottom of tower 3@ by means of line 32, while the asphalt withdrawn by means of linel 33. The deasphalted oil is removed overhead by'means oi" line 34'. The remainder of the system, not shown, is similar-to that described with respect to Figure `l. In4 accordance with this type of operation, the inter.- face level X is maintained near the point of in-` troduction of the precipitant. The precipitant phase therefore lies above levelv X and substantially completely lls tower 30, while the asphalt phase lies below level X in the extreme bottom of the tower. A partial adaptation of my process is shown in diagram B. All lines in the units of. diagrams B and C are entirely similar to those. described in diagram A and are identied by the same numbers. rIhe difference is that the inter-- face level Y in B is maintained at an intermediate point in the treating tower, causing the asphalt phase to extend part way up the tower 30. Diagram C illustrates an operation fully in accordance-with my invention. Here the interface level is near the top of the treating zone. Thisgmeans. thatv thev asphalt phase substantially.r lls the. tower comprising the continuous phasel rather than the precipitant phase.

Referring now to Figure 3, this gure illustrates my process embodying two treating zones wherein asphalts of different softening points are segregated in the respective zones. Although only two zones are shown, it is to be understood that any number of zones may be also utilized. The residuum feed is introduced into zone 5S by means of line 5 Conditions are adjusted so that the interface level in zone 50 is near the top of the treating zone at approximately level W. Precipitant such as butane is introduced into zone 50 by means of line 52 and the asphalt is withdrawn by means of line 53. An oil phase is removed from zone 50 by means of line 54 and is introduced into secondary treating zone 6E). rlemperature conditions are adjusted in zone 50 to secure further precipitation of asphaltic type materials which are lremoved by means of line 6|. The completely deasphalted oil is removed from Zone Sil by means of line 52 and handled as described With Vrespect* to Figure 1. The first stage of this process operates substantially'as described.V in regard to Figure 1. However, the temperature in the rst stage, tower 59, is maintained below the optimum'temperature for completepre'- cipitation. Consequently the harder asphalt, having'a higher softening point, is precipitated in this stage, leaving lower softening vpoint asphalt in the oil. The temperature of the second'stagc is maintained' at a higher range` so that all remaining' asphalt will be precipitatedfrom*l the oil in the second stage. Bythis means fractionation of the asphalt is obtained. Iny effect these two stages. providev refluxing of the resi-duum both above andA below'the point of introduction of YtheV residuum. The use of two stages permits a greater overall temperature Vgradient and more favorable treating conditions thany is practical in a one stage process.

My invention is concerned with theuse of the asphalt phase as the continuousv phase 'in the removal of asphaltic type materials from mineral oils, particularly heavy petroleum residua. It is particularly adapted to the countercurrent treatment of asphalt-containing mineral oil stocks with propane, butane, or other liquied light hydrocarbons in vertical treating towers: By operatingA as' described, marked improvements vin efficiencies are obtained, particularly with respect to the amount of asphaltic materials and ash remaining inthe treated oil. On the otherhand, if oils are run according to this invention to secure the same ash content, marked improve'- ment in the yield will be secured. This is readily apparent by the following example:

Asphalt phase vs. precipitant phase deasphalting, of WestTexas residaam Itwill be noted that when using 400 vol.v per centv propane with treating conditions adjusted; to give a deasphalted oil having 3 pounds ash/MB, an 11% higher yield v(67% v s. 56%

yield) resulted operating according to this invention with a continuous asphalt phase; similarly, with 600-800 vol. per cent propane and treating conditions adjusted to yield a product having 3 pOunds ash/MB, the yield was increased 5% (72 `vs. 67% yieldiwhen employing a continuous vasphalt phase. Stated another way, comparing columns l and 4, When using the process of this invention, much less precipitant was required to produce a fixed yield and quality of product. It follows, therefore, that where the production of desasphalted oil in a given plant installation is limited solely by the amount of precipitant which can be circulated, use of the process of this invention will permit a 50 to 100% increase in the production of deasphalted oil.

While the description has been directed primarily to the use of propane as the precipitant, butane is also satisfactory, and, in the case of certain oil residua, is to be preferred to propane. This invention is also applicable to two solvent processes, in which the residuum is introduced at duction of the oil residuum may be varied but it is preferred to introduce the residuum near the point of the deasphalted oil withdrawal. It is alsol preferred that the asphalt phase extend substantially up the tower to the point of introduction of the residuum although some of the benets of this invention may be appreciated by any increase in the height of the asphalt phase over that of conventional processes.

Having now fully described my invention, what I claim and desire to protect by Letters Patent is:

1. A process for precipitating asphaltic and metallic substances from petroleum oil compri'sing contacting the oil in a treating zone with a precipitant selected from the class consisting of liquefied propane and butane, said treating zone being dened by the points of oil and precipitant introduction, the process being characterized by the introduction of preoipitant at the bottom of the said zone, the introduction of petroleum oil at the top of said zone, the withdrawal of a pre cipitated asphaltic phase from the bottom of said Zone, the withdrawal of treated petroleum. oil from the top of said zone, and the maintenance of the said precipitated asphaltic phase substantially throughout the said treating zone.

2. A process for precipitating asphaltic and metallic substances from a heavy residual oil obtained from the distillation of petroleum oils, comprising contacting the oil in a treating zone with a precipitant selected from the class consisting of liquefied propane and butane, said treating zone being deiined by the points of oil and pre.- cipitant introduction, the process being characterized by the introduction of precipitant at the bottom of the said zone, the introduction of oil at the top of said zone, the withdrawal of a precipitated asphaltic phase from the bottom of said zone, the withdrawal of treated oil from the top of said zone, and the maintenance of the said precipitated asphaltic phase substantially throughout the said treating zone.

3. A process in accordance with claim 1 wherein the precipitant consists of propane and a temperature of about to 180 F., and afpressure of about 400 to 600 p. s. i. is maintained.

4. A process in accordance with claim 1 wherein the precipitant consists of butane, and a temperature of about 90 to 305 F., and a pressure of about 400 to 600 p. s. i. is maintained.

EARL E. WILLAUER.

REFERENCES CITED The following references are of record in the Iile of this patent:

UNITED STATES PATENTS Dickinson et al Jan, 23, 1945 

1. A PROCESS FOR PRECIPITATING ASPHALTIC AND METALLIC SUBSTANCES FROM PETROLEUM OIL COMPRISING CONTACTING THE OIL IN A TREATING ZONE WITH A PRECIPITANT SELECTED FROM THE CLASS CONSISTING OF LIQUEFIED PROPANE AND BUTANE, SAID TREATING ZONE BEING DEFINED BY THE POINTS OF OIL AND PRECIPITANT INTRODUCTION, THE PROCESS BEING CHARACTERIZED BY THE INTRODUCTION OF PRECIPITANT AT THE BOTTOM OF THE SAID ZONE, THE INTRODUCTION OF PETROLEUM OIL AT THE TOP OF SAID ZONE, THE WITHDRAWAL OF A PRECIPITATED ASPHALTIC PHASE FROM THE BOTTOM OF SAID ZONE, THE WITHDRAWAL OF TREATED PETROLEUM OIL FROM THE TOP OF SAID ZONE, AND THE MAINTENANCE OF THE SAID PRECIPITATED ASPHALTIC PHASE SUBSTANTIALLY THROUGHOUT THE SAID TREATING ZONE. 